Alignment mark evaluation method and alignment mark evaluation system

ABSTRACT

Embodiments of the present disclosure provide an alignment mark evaluation method and an alignment mark evaluation system. The alignment mark evaluation method includes: setting a process step code of a wafer with an alignment mark to be evaluated as an evaluation code; obtaining a current process step code of the wafer; if it is detected that the current process step code is the evaluation code, switching a step to be executed to an alignment mark evaluation step; and executing the alignment mark evaluation step to evaluate the alignment mark to be evaluated.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present disclosure claims the priority to Chinese Patent Application202010954861.9, titled “ALIGNMENT MARK EVALUATION METHOD AND ALIGNMENTMARK EVALUATION SYSTEM”, field to the CNIPA on Sep. 11, 2020, which isincorporated herein by reference in its entirety.

TECHNICAL FIELD

Embodiments of the present disclosure relate to, but are not limited to,an alignment mark evaluation method and an alignment mark evaluationsystem.

BACKGROUND

An appropriate light source and an appropriate alignment mark arerequired during exposure. The quality of an alignment mark signaldetermines whether a wafer can be normally exposed, as well as exposureaccuracy and exposure stability. When new products are developed,optimal alignment marks need to be selected from optional alignmentmarks, so as to improve the exposure stability between different wafersin the same lot and between different wafer lots.

SUMMARY

The following is the summary of subject matters detailed in the presentdisclosure. The summary is not intended to limit the protection scope ofthe claims.

Embodiments of the present disclosure provide an alignment markevaluation method and an alignment mark evaluation system, which arebeneficial to improving the evaluation efficiency of an alignment mark.

An embodiment of the present disclosure provides an alignment markevaluation method, including: setting a process step code of a waferwith an alignment mark to be evaluated as an evaluation code; obtaininga current process step code of the wafer; if it is detected that thecurrent process step code is the evaluation code, switching a step to beexecuted to an alignment mark evaluation step; and executing thealignment mark evaluation step to evaluate the alignment mark to beevaluated.

According to some embodiments of the present disclosure, setting theevaluation code includes: setting a process step code of a wafer lotincluding a plurality of wafers as the evaluation code, the wafer lothaving the alignment mark to be evaluated; obtaining the current processstep code includes: obtaining the current process step code of the waferlot. In this way, the stability of alignment marks of different wafersin the same lot can be obtained by analyzing the evaluation data.

According to some embodiments of the present disclosure, the wafer has aplurality of the alignment marks to be evaluated; evaluating thealignment marks to be evaluated includes: evaluating each of thealignment marks to be evaluated. In this way, evaluation data of theplurality of alignment marks can be obtained at the same time.

According to some embodiments of the present disclosure, before theexecuting the alignment mark evaluation step, the method furtherincludes: setting a mask code as a virtual mask code to skip a photomaskloading step; wherein the mask code is configured to specify a photomaskto be loaded, and the virtual mask code does not specify the photomask.In this way, the mask may not be provided when the alignment mark isevaluated, which can reduce the total steps of the evaluation method,avoid damage to the mask, and prolong the service life of the mask.

According to some embodiments of the present disclosure, the alignmentmark evaluation method further includes: setting a first mask code ofthe wafer as the virtual mask code; the setting a mask code as a virtualmask code includes: reading the first mask code to set a second maskcode for specifying a photomask as the virtual mask code. As such, thesecond mask code can be virtualized by adjusting the first mask code ofthe wafer.

According to some embodiments of the present disclosure, the alignmentmark evaluation method further includes: establishing a dynamic pathconnecting the wafer and an equipment, the equipment being configured toobtain the process step code and execute the alignment mark evaluationstep;

and controlling the wafer to be transferred along the dynamic path afterestablishing the dynamic path.

According to some embodiments of the present disclosure, after theevaluation, the wafer is controlled to be transferred to a nextequipment along the dynamic path; the method further includes: obtainingthe current process step code of the wafer, and transferring the waferif the current process step code is the evaluation code.

Correspondingly, an embodiment of the present disclosure furtherprovides an alignment mark evaluation system, including: a compilingmodule, configured to set a process step code of a wafer with analignment mark to be evaluated as an evaluation code; and a processequipment, configured to obtain a current process step code of thewafer, switch a step to be executed to an alignment mark evaluation stepif it is detected that the current process step code is the evaluationcode, and execute the alignment mark evaluation step to evaluate thealignment mark to be evaluated.

According to some embodiments of the present disclosure, the alignmentmark evaluation system further includes: a wafer lot, the wafer lotincluding a plurality of wafers; the compiling module is furtherconfigured to set a process step code of the wafer lot as an evaluationcode; the process equipment is further configured to obtain a currentprocess step code of the wafer lot.

According to some embodiments of the present disclosure, the processequipment is further configured to set a mask code as a virtual maskcode to skip a photomask loading step; wherein the mask code isconfigured to specify a photomask to be loaded, and the virtual maskcode does not specify the photomask.

According to some embodiments of the present disclosure, the alignmentmark evaluation system further includes: a management module, configuredto establish a dynamic path connecting the wafer and the processequipment, and also configured to control the wafer to be transferredalong the dynamic path.

According to some embodiments of the present disclosure, the alignmentmark evaluation system further includes: a process matching equipment,the process matching equipment being located behind the processequipment in the transfer direction of the wafer; the process matchingequipment is configured to obtain the current process step code of thewafer, and is also configured to transfer the wafer when the currentprocess step code is the evaluation code.

According to some embodiments of the present disclosure, the processequipment includes an exposure equipment; and the process matchingequipment includes a developing equipment.

Compared with the prior art, the technical solutions provided by theembodiments of the present disclosure have the following advantages:

In the above technical solutions, a step code of a specific wafer isadjusted, and the alignment mark evaluation step can be automaticallyenabled by identifying the step code of the wafer. As such, thealignment mark evaluation step can be remotely operated, and thealignment mark evaluation step and other parallel steps can be switched,without a special equipment for the alignment mark evaluation step,which is beneficial to improving the evaluation efficiency of thealignment mark.

Other aspects will be apparent upon reading and understanding theaccompanying drawings and detailed descriptions.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings incorporated into the description andconstituting a part of the description illustrate the embodiments of thepresent disclosure, and are used together with the description toexplain the principles of the embodiments of the present disclosure. Inthese drawings, similar reference numerals are used to indicate similarelements. The drawings in the following description are some embodimentsof the present disclosure, but not all embodiments. For those skilled inthe art, other drawings can be obtained from these drawings without anycreative efforts.

FIG. 1 is a schematic flowchart of an alignment mark evaluation methodprovided by an embodiment of the present disclosure;

FIG. 2 is a schematic distribution diagram of an alignment markevaluation system provided by an embodiment of the present disclosure.

REFERENCE NUMERALS

201: wafer; 202: compiling module; 203: management module; 204: processequipment; 205: process matching equipment.

DETAILED DESCRIPTION

In order to make the objectives, technical solutions and advantages ofthe embodiments of the present disclosure clearer, the embodiments ofthe present disclosure will be described in detail below with referenceto the accompanying drawings. However, those skilled in the art canunderstand that, in each embodiment of the present disclosure, manytechnical details are proposed in order to enable a reader to betterunderstand the present disclosure. However, the technical solutions ofthe present disclosure can also be implemented without these technicaldetails and various variations and modifications based on the followingembodiments.

FIG. 1 is a schematic flowchart of an alignment mark evaluation methodprovided by an embodiment of the present disclosure. Referring to FIG.1, the alignment mark evaluation method includes:

Step 101: a step code of a wafer with an alignment mark to be evaluatedis set as an evaluation code.

In some embodiments of the present disclosure, the wafer has analignment mark, the information directory of the wafer includes theattribute column “process step code”, the text information correspondingto the attribute column of the process step code includes an evaluationcode or a process code, the evaluation code is used to characterize thatthe wafer requires an alignment mark evaluation, and the process code isused to characterize that the wafer requires a preset process.

The evaluation code may be a specific character string, such as/MONITOR/ALE, and the process code may also be a specific characterstring, such as/DBRMA/ART01.

When a plurality of wafers are transferred one by one on a preset trackfor a preset process, a process step code(s) of one or more of thewafers may be individually set, thus obtaining the accuracy of analignment mark of a single wafer and the stability of alignment marksbetween different wafers; when wafers are transferred on a preset trackin the form of wafer lots, a process step code(s) of one or more waferlots may be set to perform an alignment mark evaluation step on allwafers of the wafer lot(s), thus obtaining the repeatability ofalignment marks of different wafers in a single wafer lot and thestability of alignment marks between different wafer lots by analyzingevaluation data.

A wafer usually has a plurality of alignment marks, and the alignmentmarks may include one or more alignment marks to be evaluated. When thealignment marks are subsequently evaluated, each alignment mark to beevaluated is evaluated to obtain original signal data of each alignmentmark to be evaluated, and then an optimal alignment mark is screenedout. This is advantageous to further improve the evaluation efficiencyof the alignment mark to be evaluated.

Step 102: a dynamic path is established, and the wafer is controlled tobe transferred along the dynamic path.

The dynamic path is used to connect a wafer position and an equipmentposition, so that the wafer or wafer lot can be transferred to thepreset equipment position, wherein the equipment is configured to obtaina current process step code of the wafer or wafer lot and execute analignment mark evaluation step. The equipment for the alignment markevaluation step may be either a special equipment only used to executethis step, or any equipment that is idle or about to be idle and canexecute this step. The latter option can increase the utilization of theequipment and increase the uptime of the equipment, thereby increasingthe output.

The equipment includes a process equipment, the process equipment refersto an equipment that can perform a preset process, and the processequipment includes an exposure equipment.

After the dynamic path is established, both wafers with alignment marksto be evaluated and wafers without alignment marks to be evaluated canbe controlled to be transferred along the dynamic path. This can reducethe difficulty in establishing the dynamic path, improve the utilizationof the wafer transfer path, and quickly implement the evaluation stepfor alignment marks.

Step 103: a current process step code of the wafer is obtained.

In some embodiments of the present disclosure, after the wafer or waferlot is transferred to a detection range or a process range of theequipment, the equipment obtains the current process step code of thewafer by reading an information directory of the wafer or wafer lot. Thedetection range refers to a position range where the equipment can readinformation, the process range refers to a position range where thewafer or wafer lot should be located for the preset process or thealignment mark evaluation step, and the process range is usually smallerthan the detection range.

The equipment adjusts a step to be executed according to the readcurrent process step code. When the current process step code is theevaluation code, step 105 is executed; when the current process stepcode is the process code, step 104 is executed.

The preset process is related to the specific type of the equipmentexecuting the alignment mark evaluation step. For example, when theequipment executing the alignment mark evaluation step is an exposureequipment, the preset process is exposure.

Step 105: a step to be executed is switched to an alignment markevaluation step.

When the current process step code of the wafer is the evaluation code,the step to be executed may be switched from the preset process to thealignment mark evaluation step, or the step to be executed may beswitched from a first alignment mark evaluation step to a secondalignment mark evaluation step, and the difference between the firstalignment mark evaluation step and the second alignment mark evaluationstep lies in different alignment marks to be evaluated.

The alignment mark evaluation step is used to obtain evaluation data ofthe alignment mark to be evaluated, the evaluation data including theaccuracy of the alignment mark to be evaluated. After evaluation data ofa plurality of different alignment marks to be evaluated in the samescenario is obtained, alignment marks with relatively high accuracy maybe selected as alignment marks actually applied to the scenario. Inaddition, after multiple evaluations on the different alignment marks tobe evaluated in the same scenario, alignment marks with better stabilitymay be selected as alignment marks actually applied to the scenario.

In addition, when the wafer has a plurality of alignment marks, themethod of obtaining the alignment mark to be evaluated includes: firstevaluating all the alignment marks, and then screening evaluation dataof the alignment mark to be evaluated from the obtained evaluation data;or, first locating the alignment mark to be evaluated, and thenevaluating the alignment mark to be evaluated.

Step 106: a mask code is set as a virtual mask code.

After the equipment detects the evaluation code, the step to be executedis switched to the alignment mark evaluation step instead of the presetprocess, so a specified mask is no longer required, that is, a mask isno longer called to limit the process range of the equipment.

When the equipment is an exposure equipment, the mask is a photomask,and the photomask is used to limit the range of light irradiated on thewafer.

The mask code is used to specify a photomask to be loaded, while thevirtual mask code does not specify the photomask. After the mask code isset as the virtual mask code, a photomask calling step can be skipped.In this way, the mask may not be provided when the alignment mark isevaluated, which can reduce the total steps of the evaluation method,avoid damage to the mask, and prolong the service life of the mask.

The information directory of the wafer or wafer lot includes anattribute column “first mask code”, which is used to indicate aphotomask required for the wafer or wafer lot; the equipment has anattribute column “second mask code”, which is used to specify aphotomask to be loaded; and the equipment can call the specifiedphotomask by reading text information of the first mask code and settingthe text information of the first mask code as text information of thesecond mask code.

The step of calling the photomask is not necessarily performed by theequipment, but can also be performed by other control module. That is,the control module reads the second mask code of the equipment and callsthe specified photomask according to the second mask code.

Since the photomask does not need to be called when the wafer with thealignment mark to be evaluated is evaluated, the first mask code may beset as a virtual mask code, and the second mask code identical to thefirst mask code is also a virtual mask code, thus skipping the step ofcalling the photomask; or, after the equipment reads the first maskcode, the equipment can directly account for the equipment, that is,directly adjust the second mask code to a virtual mask code, thusskipping the step of calling the photomask.

In the case of directly accounting for the equipment, regardless ofwhether the first mask code is a virtual mask code or a valid mask codespecifying a specific mask, the second mask code can be set as a virtualmask code. In this way, when the process step code of the wafer or waferlot is set as the evaluation code, and the first mask code is notadjusted to the virtual mask code, the step of calling the mask can beskipped.

Step 107: the alignment mark evaluation step is executed.

Since the wafer or wafer lot is only used for the alignment markevaluation step at this time, the process equipment used to execute thealignment mark evaluation step does not need to execute the presetprocess, and the matching process equipment matching the processequipment also does not need to execute the preset matching processstep, and the both are only used for the wafer or wafer lot transferstep.

The process equipment may be an exposure equipment, and the matchingprocess equipment may be a developing equipment. On the transfer path ofthe wafer or wafer lot, after the wafer or wafer lot completes thealignment mark evaluation step at the process equipment, the developingequipment obtains the current process step code of the wafer. If thecurrent process step code is the evaluation code, the developingequipment does not execute, but is only used to transfer the wafer orwafer lot.

In some embodiments of the present disclosure, a step code of a specificwafer is adjusted, and the alignment mark evaluation step can beautomatically enabled by identifying the step code of the wafer. Assuch, the alignment mark evaluation step can be remotely operated, andthe alignment mark evaluation step and other parallel steps can beswitched, without a special equipment for the alignment mark evaluationstep, which is beneficial to improving the evaluation efficiency of thealignment mark.

Correspondingly, an embodiment of the present disclosure furtherprovides an alignment mark evaluation system, which can be used toexecute the above alignment mark evaluation method.

Referring to FIG. 2, the alignment mark evaluation system includes: acompiling module 202, configured to set a process step code of a wafer201 with an alignment mark to be evaluated as an evaluation code; and aprocess equipment 204, configured to obtain a current process step codeof the wafer 201, switch a step to be executed to an alignment markevaluation step if it is detected that the current process step code isthe evaluation code, and execute the alignment mark evaluation step toevaluate the alignment mark to be evaluated.

The wafer 201 may be a single wafer or a wafer lot, and the wafer lotincludes a plurality of wafers; the compiling module 202 is furtherconfigured to set a process step code of the wafer lot as an evaluationcode, and the process equipment 204 is further configured to obtain acurrent process step code of the wafer lot.

The process equipment 204 is further configured to set a mask code as avirtual mask code to skip a photomask loading step; wherein the maskcode is configured to specify a photomask to be loaded, and the virtualmask code does not specify the photomask.

In some embodiments of the present disclosure, the alignment markevaluation system further includes: a management module 203, configuredto establish a dynamic path connecting the wafer 201 and the processequipment 204, and also configured to control the wafer 201 to betransferred along the dynamic path.

The alignment mark evaluation system further includes: a processmatching equipment 205, the process matching equipment 205 being locatedbehind the process equipment 204 in the transfer direction of the wafer201; the process matching equipment 205 is configured to obtain acurrent process step code of the wafer 201, and suspend the execution ofa preset process when the current process step code is the evaluationcode.

The process equipment includes an exposure equipment; and the processmatching equipment includes a developing equipment.

In some embodiments of the present disclosure, an alignment markevaluation system is provided. A step code of a specific wafer isadjusted, and the alignment mark evaluation step can be automaticallyenabled by identifying the step code of the wafer. As such, thealignment mark evaluation step can be remotely operated, and thealignment mark evaluation step and other parallel steps can be switched,without a special equipment for the alignment mark evaluation step,which is beneficial to improving the evaluation efficiency of thealignment mark.

A person skilled in the art would easily conceive of other embodimentsof the present disclosure after considering the disclosure of thedescription and practice. The present disclosure is intended to coverany variations, uses or adaptive changes of the present disclosure.These variations, uses or adaptive changes follow the general principleof the present disclosure and comprise common general knowledge orconventional technical means in the technical field that are notdisclosed in the present disclosure. The description and the embodimentsare merely regarded as exemplary, and the real scope and spirit of thepresent disclosure are pointed out by the following claims.

Those skilled in the art can understand that the foregoing embodimentsare specific examples for implementing the present disclosure, and inactual applications, various changes may be made in form and detailswithout departing from the spirit and scope of the present disclosure.Any person skilled in the art can make various changes and modificationswithout departing from the spirit and scope of the present disclosure.Therefore, the protection scope of the present disclosure shall besubject to the scope of the claims.

INDUSTRIAL APPLICABILITY

The embodiments of the present disclosure provide an alignment markevaluation method and an alignment mark evaluation system. A step codeof a specific wafer is adjusted, and the alignment mark evaluation stepcan be automatically enabled by identifying the step code of the wafer.As such, the alignment mark evaluation step can be remotely operated,and the alignment mark evaluation step and other parallel steps can beswitched, without a special equipment for the alignment mark evaluationstep, which is beneficial to improving the evaluation efficiency of thealignment mark.

1. An alignment mark evaluation method, wherein the alignment markevaluation method comprises: setting a process step code of a wafer withan alignment mark to be evaluated as an evaluation code; obtaining acurrent process step code of the wafer; if it is detected that thecurrent process step code is the evaluation code, switching a step to beexecuted to an alignment mark evaluation step; and executing thealignment mark evaluation step to evaluate the alignment mark to beevaluated.
 2. The alignment mark evaluation method according to claim 1,wherein setting the evaluation code comprises: setting a process stepcode of a wafer lot comprising a plurality of wafers as the evaluationcode, the wafer lot having the alignment mark to be evaluated; obtainingthe current process step code comprises: obtaining the current processstep code of the wafer lot.
 3. The alignment mark evaluation methodaccording to claim 1, wherein the wafer has a plurality of the alignmentmarks to be evaluated; evaluating the alignment marks to be evaluatedcomprises: evaluating each of the alignment marks to be evaluated. 4.The alignment mark evaluation method according to claim 1, whereinbefore the executing the alignment mark evaluation step, the methodfurther comprises: setting a mask code as a virtual mask code to skip aphotomask loading step; wherein the mask code is configured to specify aphotomask to be loaded, and the virtual mask code does not specify thephotomask.
 5. The alignment mark evaluation method according to claim 4,wherein the alignment mark evaluation method further comprises: settinga first mask code of the wafer as the virtual mask code; the setting amask code as a virtual mask code comprises: reading the first mask codeto set a second mask code for specifying a photomask as the virtual maskcode.
 6. The alignment mark evaluation method according to claim 1,wherein the alignment mark evaluation method further comprises:establishing a dynamic path connecting the wafer and an equipment, theequipment being configured to obtain the current process step code andexecute the alignment mark evaluation step; and controlling the wafer tobe transferred along the dynamic path after establishing the dynamicpath.
 7. The alignment mark evaluation method according to claim 6,wherein after the evaluation, the wafer is controlled to be transferredto a next equipment along the dynamic path; the method furthercomprises: obtaining the current process step code of the wafer, andtransferring the wafer if the current process step code is theevaluation code.
 8. An alignment mark evaluation system, wherein thealignment mark evaluation system comprises: a compiling module,configured to set a process step code of a wafer with an alignment markto be evaluated as an evaluation code; and a process equipment,configured to obtain a current process step code of the wafer, switch astep to be executed to an alignment mark evaluation step if it isdetected that the current process step code is the evaluation code, andexecute the alignment mark evaluation step to evaluate the alignmentmark to be evaluated.
 9. The alignment mark evaluation system accordingto claim 8, wherein the alignment mark evaluation system furthercomprises: a wafer lot, the wafer lot comprising a plurality of wafers;the compiling module is further configured to set a process step code ofthe wafer lot as an evaluation code; the process equipment is furtherconfigured to obtain a current process step code of the wafer lot. 10.The alignment mark evaluation system according to claim 8, wherein theprocess equipment is further configured to set a mask code as a virtualmask code to skip a photomask loading step; wherein the mask code isconfigured to specify a photomask to be loaded, and the virtual maskcode does not specify the photomask.
 11. The alignment mark evaluationsystem according to claim 8, wherein the alignment mark evaluationsystem further comprises: a management module, configured to establish adynamic path connecting the wafer and the process equipment, and alsoconfigured to control the wafer to be transferred along the dynamicpath.
 12. The alignment mark evaluation system according to claim 9,wherein the alignment mark evaluation system further comprises: aprocess matching equipment, the process matching equipment being locatedbehind the process equipment in the transfer direction of the wafer; theprocess matching equipment is configured to obtain the current processstep code of the wafer, and is also configured to transfer the waferwhen the current process step code is the evaluation code.
 13. Thealignment mark evaluation system according to claim 12, wherein theprocess equipment comprises an exposure equipment; and the processmatching equipment comprises a developing equipment.